Fluid pressure control



May 19, 1931. H. u. DURANT 1,805,814

FLUID PRESSURE CONTROL Filed March 5, 1929 1 N V EN TOR.

.4 TTORNE Y.

Patented May 3 UNITED STA- ,nnnnnm u. roam, or Los menus, cnmnoma rmrrornnsscnn con'rnor.

This invention Application fled nmn 5,1029. Serial in. 844,101.

is a valve for regulating pressure, and has for its object to provide apredetermined pressure in accordance with movement of a suitablecontrol, and

maintain thepredetermined pressure as long as the position of thecontrol remains unchanged. While the embodiment of the invention hereinillustrated and described is particularly. adapted for use in connectionapplication, Ser.

with a fluid pressure operating means for vehicle brakes as set forth inmy copending No. 344,190, filed March 5, 1929, it will be apparentfromthe-following description that the invention is of general applicationmatically maintaining a for regulating and autopressure for any type offluid pressure operated mechanism.

It is a further object of the invention to not only regulate anduniformly maintain a pressure in accordance with the positioning of asuitable control, but also gradually and uniformly increase or decreasethe pressure in accordance with corresponding movement of the control,thereby particularly adapting the invention for use in connection withfluid pressure power appliances such as the vehicle brake oper atingmechanism described in my above mentioned copending application, whereit is movement of the control device in either of desirable thatcontinued opposite directions will produce a gradually increasingordecreasing fluid pressure, and will uniformly maintain the samewithout further manipulation when movement of the control is stopped atany pre determined point.

' It is a still further object of the invention to provide foradjustment of the control valve so that wh its limit of movement it willpermit the 'flow of only a eu it has been shifted to predeterminedmaximum pressure irrespective of the actuating force which may beexerted against the control. In its application to fluidpressure brakesthe invention will thus permit of the control valve being so adjustedthat in no event will the pressure. lock the brakes skid. j

developed be suflicient to and cause the vehicle to predetermined It isa still further object of the invention to ada t the control formanipulation with little e ort, as is particularly desirable when usedin connection with vehicle brakes where road fatigue incident torepeated brake applications is often excessive; but the apparatusprovides some resistance to free movement of the control, with'theresistance varying in accordance with the pressure application resultingfrom its mampulation, in order that the operator may be relativelyadvised as to the power application by the resistance felt in actuatingthe control. In its use in connection with vehicle brake mechanism theinvention thus providesfor applying the brakes with the driver sensingthe braking efii'ect-by the resistance encountered in depressing apedal,

as in the usual practice, but the driver isv relieved of all excessivephysical exertion. through substitution of fluid pressure opera," tionfor the usual manual actuation.

' The invention preferably also provides a for adjusting the initialresistance encountered in actuating the control, so as to adapt thedevice to the individual users sense of feeling, as is particularlydesirable in sensingthe application of vehicle brakes; and the controlmay also be arranged for ad.- justment of its actuating means so thatwhen the invention is employed in connection with vehicle brakes, theactuating means which will preferably be in the form of an ordinarybrake pedal may be made readily accessible to the drivers foot,preferably alongside the 35 I the coneluding a rock shaft 1 providedwith brake rods 2 for operating the usual vehicle brakes (not shown),the lever 3 for rocking the shaft being in the present instance adaptedfor actuation by either a rod 4 or by the usual foot pedal 5. Brakepedal 5 instead of being integral with lever 3 as in the usualconstruction, is preferably pivoted to the lever close to its fulcrum 1as shown at 6, with a spring 5 tending to retract the pedal as shown inFig. 1 so that the brakes may be actuated by axial movement of rod 4without appreciably moving the usual brake pedal, or the brake pedal maybe depressed and engage lever 3 by means of a bracket 7 so as to actuatethe brakes in usual manner. Rod 4 is adapted for axial depressionresponsive to fluid pressure for applying the brakes, and as an instanceof this arrangement is shown telescoping in the piston rod 8" of apiston 8 which reciprocates in a cylinder 9 which may be mounted on theback of the dash 10 of the vehicle.

The end of piston rod 8 is adapted to abut against a pin 65 projectingfrom rod 4 and preferably adjustable axially of said rod, as for exampleby spacing transverse bores 4 along the lengths of the rod with the pin65 ada ted for selective reception in said bores. 2 spring 3 tends toretract lever 3 and normally yieldably telescopes rod 4 relative topiston rod 8 so that pin 65 abuts against the end of the piston rod forelevating piston 8 in its cylinder 9 as shown in Fig. 1. The lever 3 maythus be actuated by depression of piston 8 in its cylinder or may bemanually actuated by pedal 5 without disturbing the piston, due to thetelescopic engagement 48 Fluid pressureis supplied to cylinder 9 througha conduit 11 connected to the discharge 12 of the control valve formingthe subject matter of the present invention, and this control valve hasan intake 13 connected by conduit 14 to a source of fluid pressuresupply shown as a compressed air tank 15. The control valve is alsoprovided with s an exhaust 16 leading to the atmosphere,

and the valve is so arranged as to close exhaust'16 and open intake 13to discharge 12 for supplying fluid pressure to cylinder 9 for axiallymoving rod 4 and thereby applying the brakes, or may be shifted so as toclose intake 13 and open discharge 12 to the exhaust 16 for relievingthe pressure in cylinderg9 so that spring 3 may release the brakes. V

The control valve preferably comprises a cylinder 20 adapted formounting on the front of dash 10 by means of bolts 21, and closed at itsupper end bya cap forming a. valve casing 22 for-a usual three-wayvalve. The lower end of'the cylinder may receive a rotatably adjustableported plug 23 having a depending and radially projecting 20, and acoilspring 29 engages the underside of the piston with its lower end supported on a collar 30 carried by a pll ltllnger 31 which projectsthrough plug .23. e plunger is adapted for abutment by lever arm 32 ofthe foot pedal, so that with the foot pedal in normal position as shownin Fig. I 2 the plunger may be depressed vwith its collar 30 restingupon a guide sleeve'33 of plug 23, andkdepression of thefoot pedal willshift the plunger upwardl in the cylinder 20 as hereinafter describedThe valve casing 22 preferably has diametrically opposite intake anddischarge ports 35 and 36 and an exhaust ort 37 at right angles thereto,with the inta e and exhaust ports 35 and 37 communicating with nippleson casing 22 forming the intake 13 and exhaust 16 respectively. Thedischarge port 36 opens into cylinder 20 which is provided adjacent itsupper end with a nipple forming the discharge 12. -The three-way valvein casing 22 may be a usual tapered cylinder 38 closed at its ends androtatable in the valve casing, and is provided with circumferentiallyspaced per pheral ports 39- 4041 forming an intake, discharge andexhaust respectively. These ports are so positioned that alinement ofport 41 with exhaust 37 will close port 39 to intake 35 and open port 40to discharge 36 as shown in Fig. 2, and partial rotation of the valvewill first close port 41 to exhaust 37 and will thenopen port 39 tointake 35 while main taining port 40 in-open communication withdischarge 36. With the parts in the position shownin Fig. 2 the ressuresupply from tank 15 is thus cut-oil from cylinders 9 and 20, and thesecylinders discharge to the atmosphere through exhaust 16 so that nooperating pressure is applied through rod 4 to the brake lever 3.Byturning the valve 38, the exhaust 16 is first closed and intake 13'isthen opened for supplying pressure to cylinders 9 and 20. The pressurein cylinder 9 will axially move rod 4 for operating the vehicle brakesthrough swinging movement of 'lever 3, and the corresponding pressure incylinder, 20 against piston 27 will tend to depress the piston againstthe'yielding resistance of spring 29 in order to regulate the pressureby controlling valve 38 as will now be described.

The means for controllin and operating valve 38 includes usual roc glever arms 34 on the valve, which are pivoted at 46 to alinkv 47extending alongside the cylinder 20. The lower end of the link is forkedat 48 and connected to studs 49 which project respective ends to link 47and cylinder 20 so as to tend to depress the link and thereby positionthe valve 38 in its ino erative posit1on as shown'in Fig. 2, and t ismovement of the link lowers piston 27 in cylinder 20 until it issupportedon spring 29 with the latter in normal expand-e position withits collar 30 resting on guide sleeve 33.

The tension of spring-'51 is preferably adjustable, as for-exampleas.shown at 52, and the spring may be guided and protected by channelinglink 47' so as to partially surround the spring. A further adjustmentfor the device comprises a sto 53, preferably axially adjustable in ug'23 by a threaded connection 54, an adapted for abutment of lever arm 32against its depending head for limiting depression of foot pedal 25 andthe correspondingelevatmn of plunger 31. The ported plug 23 may belocked in rotatably adjusted position relative to cylinder 20 by setscrews extending through the cyllnder wall and seating in an annularoove 56 in the plug, and the plug is so a justed as to ro'ect the footedal 25 at any desired ang e or-positionmg it convenient to the foot ofthe driver of the vehicle, preferably closely adjacent the usualaccelerator so that without changing the position of the heel and bysimply later ally swinging the foot it may readily engage either thefoot pedal 25 or the accelerator.

' v The foot pedal 25 is preferably provided with an arm 60 adapted forengagement with cylinder 20 to prevent accidental upward swing of thepedal beyond its normal inoperative position shown in Fig. 2.

In operation, the vehicle brakes may be applied in usual manner bydepressing brake pedal 5, with a lost motionconnection in rod 4preferably permitting operative swinging of lever 3 without movingpiston 8 in cylinder 9, or the brakes may be applied by fluid pressuredirected against piston 8 and regulated by depressing foot pedal 25.Normal inoperative position of the pressure control is shown in Fig. 2,the spring 51 having shifted link 47 so as to move valve 38 to positionshutting off the fluid pressure and exhausting'cylinders 9 and 20 to theatmosphere, and moving piston 27 to a position where it is supported onspring 29 which is in normal expanded position with its plunger 31depressed so as to swing foot pedal 25 ment. v l Depression of pedal 25elevates plunger 31 and until there is pressure resistance againstpiston 27 the spring 29 remains expanded and correspondingly elevatesthe piston which in turn shifts link 47 against the relatively weaktension of spring 51. The valve.38 is thus rotated to first closeexhaust 16 and then open intake 13 for supplying fluid pressure tocylinder 20 and to its upper limit of movethence to c linder 9 foractuating rod 4 and j applying t e brakes. By means of the adjustment'52, the spring 51 is tensionedj to produce any desire slight resistanceto this depression of pedal 25, so thatthe driver of the vehicle will beadvised of the initial brake application by feeling this resistance.

As soon as intake 13 opens, the fluid pressure passing through cylinder20 on its way to cylinder 9 will offer resistance to further elevationof piston 27 and will thus. tend to compress spring 29 andcorrespondingly resist further elevation of plunger 31. by thedepression of pedal 25. If this resistance, by the increase in which thedriver judges the increasing force of the brake application, is overcomeby increased pressure on the foot pedal so as to continue the elevationof plunger 31, and spring 29, the :increased tensioning of the springwill at first maintain it expanded and will thus further elevate .piston27 so as to shift link 47 for further opening intake'13 and increasingthe fluid pressure supplied to cylinders 9 and 20. This increase inpressure will correspondingly increase the force of the brakeapplication and will also increase the resist.- ance to elevation of thepiston, and as soon as this increase in pressure against the piston isno longer overcome by a corresponding increase in the tensioningofspring-29 resulting from its continued elevation bydepressing pedal 25,the fluid pressure against the piston will compress the spring andthereby depress the piston for oppositely shifting link 47 so as toreduce the opening of intake port 39 until the pressurein cylinders 9and 20 is again balanced by the tension of the spring. If the foot pedalis held depressed at any predetermined point, the continued compressionof spring 29 and the corresponding depression of piston 27 resultingfrom the increasing pressure built up in cylinders 9 and 20, willfinally shift link 47 to a position completely closing intake 39 but notyet opening exhaust port 41, and the maximum pressure which has beenobtained in the cylinder 20 v i will thus be maintained until pedal 25is either released or-is further depressed.

If sufficiently increased force'is exerted against the foot pedal tofurther depress it,

the corresponding further elevation of plunger" .31 will increase thetension of sprmg 29 so as to overcome the pressure resistance againstthe piston and thereby again elevate the piston for reopening intakeport39, and when the tension of the spring is again overcome b the increasein pressure supplied to cy inder 20 and directed against the piston, thepiston will again be depressed inaccordance with compression of spring29 and will therebyv again gradually reduce the opening of intake port39 and will finally completely ,close the port so as to a ain maintain apressure corresponding means for yieldably resisting said'shifting to te new position to which pedal 25 has of the piston, means for movin theyieldbeen depressed. If pedal 25 is released able means so as tooppositelys ift the pisafter beingdepressed to any predetermined ton andadjust the tensioning of the yield: point, the release of the tension.against able means, and means for oscillating the spring 29 permitscomplete retraction of valve for'respectively closing and opening thepiston by the pressure againstit, and the valve by shifting the pistonin said first link 47 is thus shifted to its limit of movementioneddlrection and ',1n sald opposlte ment repositioning the parts as shownin direction. Fig. 2 with the intake closed and port 41 2. Pressureregulating means comprising open to exhaust 16 for relieving the presapiston, a three-way rotary valve having sure in c linder 20 and againrendering the an intake, a discharge and an exh s control deviceinoperative.

The pressure su plied through discharge of the piston, the valve beingadapted for 12is thus regulate b the degree of depresrotation in onedirection initially closing the sion of pedal 25, wit the resistance tothe intake and subsequently opening the exhaust force exerted a ainstthe pedal relatively or opposite rotation opening the intake withdenotin the flmd pressure which is bei g the exhaust closed, saidopening of the insupplie and with the pedal depressed to take supplyingpressure for shifting the pieany predetermined point the pressure ton ina direction tending to rotate the valve 511 ply is automaticallycontrolled so a to so as to close the intake, means for yieldably umormly maintain a corresponding preresistintg said shifting of thepiston, and determined pressure. The maximum presmeans or movin theyieldable means so as sure. The maximum pressure which may to oppositelyshi t the piston and adjust the be supplied is regulated by adju ti ttensioning of the yieldable means, said op- 53 so as to limit depressionof the foot pedal posite shlfting of the piston tendln to reto anypredetermined maximum, and whe tate the valve so as to open the. inta e.the invention is employed in connection 3- Pressure regulating meanscomprising with brake operating mechanism, the stop a rotary valve forsupplying pressure, the may be so adjusted as to provide a maximum valvebeing adapted for oscillation to open pressure supply which will notlock th and close the same means tending to rotate rakes and cause thevehicle to skid. and close the valve in accordance with in- Thebalancing of the pressure supply by crease in the ressure supply,yieldable means the tensioning of spring 29 permits accuresisting Sairotation and tendin to P- rate automatic regulation of the pressure,positely rotate and open the va ve, and and b feeling the resistance todepression means for shifting said yieldable means to of pe al 25 theoperator is definitely advised adjust the tensioning thereof. as to therelative pressure supply. The en- 4. Pressure regulating meanscomprising ergy exerted in depressing pedal 25 for ina cylinder, apiston in the cylinder, a valve creasing the pressure supply, is onlythat having an operating arm at the exterior of necessary to so increasethe tension of spring the cylinder, the valve being adapted for 29 as toovercome the pressure against piston pressure discharge to shift thepiston in one 27, and the leverage provided by the foot direction, meansfor yieldably resisting said pedal permits such tensioning of the'spring shiftin of the piston, meansfor moving y a relatively slightforce causing no apthe yie dable means so as to oppositely shiftpreciable physical exertion. the iston and adjust the tensioning of theThe invention thus provides extremely yiel able means, and a link at theexterior practical means for regulating and uniof the cylinderconnecting the piston and ormly maintaining a pressure supply which thevalve operating arm for respectively may be employed in any fluidpressure opclosing and openin the valve b shifting eratin machanism,such as vehicle brake the iston in said rst mentione direction actuatmgmeans, with the pressure accuand in said opposite direction. ratelyregulated and maintained by move- 5. Pressure regulating meanscomprising ment of a control which may be shifted with a cylinder, apiston in the cylinder, a rotary little physical efiort, but which issubject valve having an arm at the exterior of the to some slight"increasing resistance durin c linder for oscillating the valve to openor movement thereof in order to relatively a c ose the'valve, the valvewhen open being vise the operator as to the pressure WlllCh is adaptedfor pressure discharge to shift the means for oscillating the valve bymovement being supplied.

I claim: 1. Pressure regulating means comprising ably resisting saidshifting of the piston,

means for moving the yieldable means so as a piston, a rotary valveadapted for oscillato oppositely shift the piston and adjust the tion toopen or close the valve, the valve tensioning of the yieldable means, alink at when open being adapted for pressure dis.- the exterior of thecylinder connecting the 65 charge to shift the piston in one direction,piston and the valve operating arm was to 1 0 osoillate the valverespectively closing and opening the valve by shifting-the piston insaid figst mentioned direction and in said opposite direction;

